The TSA began using scanners in 2007, and it currently has 385 of the units at 68 airports. In March 2010, was one of the first U.S. airports to receive new full-body scanners, which help TSA agents detect concealed weapons and explosives. The TSA insists the X-ray for all individuals being screened, including children.

The security scanners project an ionizing X-ray beam over the body's surface, which creates an image of the passenger--sans clothes--that's viewed by a remote TSA officer. The technology allows security workers to look under a person's clothing without resorting to a hands-on, pat-down inspection. The process takes seconds versus 2 to 4 minutes for a pat-down. One of the scanner methodologies used--millimeter wave technology--blurs facial features to protect the passenger's privacy.

Flyers who refuse a scan can opt for a pat-down instead. John Tyner, a California software engineer, became an instant Web celebrity this week when he declined both a body scan and the alternative--a groin check-and then 's video camera to record the event.

Tyner famously told security agents: "If you touch my junk, I'm going to have you arrested." (He evaded the junk-groping but wasn't allowed to fly.)

Junk Shots Junked-or Not?